.TH std::max 3 "2024.06.10" "http://cppreference.com" "C++ Standard Libary"
.SH NAME
std::max \- std::max

.SH Synopsis
   Defined in header <algorithm>
   template< class T >                                    \fB(1)\fP (constexpr since C++14)
   const T& max( const T& a, const T& b );
   template< class T, class Compare >                     \fB(2)\fP (constexpr since C++14)
   const T& max( const T& a, const T& b, Compare comp );
   template< class T >                                    \fB(3)\fP \fI(since C++11)\fP
   T max( std::initializer_list<T> ilist );                   (constexpr since C++14)
   template< class T, class Compare >                     \fB(4)\fP \fI(since C++11)\fP
   T max( std::initializer_list<T> ilist, Compare comp );     (constexpr since C++14)

   Returns the greater of the given values.

   1,2) Returns the greater of a and b.
   1) Uses operator< to compare the values.
   If T is not LessThanComparable, the behavior is undefined.
   2) Use the comparison function comp to compare the values.
   3,4) Returns the greatest of the values in initializer list ilist.
   If ilist.size() is zero, or T is not CopyConstructible, the behavior is undefined.
   3) Uses operator< to compare the values.
   If T is not LessThanComparable, the behavior is undefined.
   4) Use the comparison function comp to compare the values.

.SH Parameters

   a, b  - the values to compare
   ilist - initializer list with the values to compare
           comparison function object (i.e. an object that satisfies the requirements
           of Compare) which returns true if a is less than b.

           The signature of the comparison function should be equivalent to the
           following:

           bool cmp(const Type1& a, const Type2& b);
   comp  -
           While the signature does not need to have const&, the function must not
           modify the objects passed to it and must be able to accept all values of
           type (possibly const) Type1 and Type2 regardless of value category (thus,
           Type1& is not allowed
           , nor is Type1 unless for Type1 a move is equivalent to a copy
           \fI(since C++11)\fP).
           The types Type1 and Type2 must be such that an object of type T can be
           implicitly converted to both of them.

.SH Return value

   1,2) The greater of a and b. If they are equivalent, returns a.
   3,4) The greatest value in ilist. If several values are equivalent to the greatest,
   returns the leftmost one.

.SH Complexity

   1) Exactly one comparison using operator<.
   2) Exactly one application of the comparison function comp.
   3,4) Given \\(\\scriptsize N\\)N as ilist.size():
   3) Exactly \\(\\scriptsize N-1\\)N-1 comparisons using operator<.
   4) Exactly \\(\\scriptsize N-1\\)N-1 applications of the comparison function comp.

.SH Possible implementation

                               max \fB(1)\fP
   template<class T>
   const T& max(const T& a, const T& b)
   {
       return (a < b) ? b : a;
   }
                               max \fB(2)\fP
   template<class T, class Compare>
   const T& max(const T& a, const T& b, Compare comp)
   {
       return (comp(a, b)) ? b : a;
   }
                               max \fB(3)\fP
   template<class T>
   T max(std::initializer_list<T> ilist)
   {
       return *std::max_element(ilist.begin(), ilist.end());
   }
                               max \fB(4)\fP
   template<class T, class Compare>
   T max(std::initializer_list<T> ilist, Compare comp)
   {
       return *std::max_element(ilist.begin(), ilist.end(), comp);
   }

.SH Notes

   Capturing the result of std::max by reference produces a dangling reference if one
   of the parameters is a temporary and that parameter is returned:

 int n = -1;
 const int& r = std::max(n + 2, n * 2); // r is dangling

.SH Example


// Run this code

 #include <algorithm>
 #include <iomanip>
 #include <iostream>
 #include <string_view>

 int main()
 {
     auto longest = [](const std::string_view s1, const std::string_view s2)
                    {
                        return s1.size() < s2.size();
                    };

     std::cout << "Larger of 69 and 96 is " << std::max(69, 96) << "\\n"
                  "Larger of 'q' and 'p' is '" << std::max('q', 'p') << "'\\n"
                  "Largest of 010, 10, 0X10, and 0B10 is "
               << std::max({010, 10, 0X10, 0B10}) << '\\n'
               << R"(Longest of "long", "short", and "int" is )"
               << std::quoted(std::max({"long", "short", "int"}, longest)) << '\\n';
 }

.SH Output:

 Larger of 69 and 96 is 96
 Larger of 'q' and 'p' is 'q'
 Largest of 010, 10, 0X10, and 0B10 is 16
 Longest of "long", "short", and "int" is "short"

   Defect reports

   The following behavior-changing defect reports were applied retroactively to
   previously published C++ standards.

     DR    Applied to              Behavior as published               Correct behavior
   LWG 281 C++98      T was required to be CopyConstructible for       not required
                      overloads (1,2)

.SH See also

   min         returns the smaller of the given values
               \fI(function template)\fP
   minmax      returns the smaller and larger of two elements
   \fI(C++11)\fP     \fI(function template)\fP
   max_element returns the largest element in a range
               \fI(function template)\fP
   clamp       clamps a value between a pair of boundary values
   \fI(C++17)\fP     \fI(function template)\fP
   ranges::max returns the greater of the given values
   (C++20)     (niebloid)
